I don't even know if a lot of riders could tell the difference. If I had a 140mm Bomber z2 at home and was buying this bike (with intention to run a 150mm fork), I would be hard pressed to shell out for a different fork. That said, if you don't own anything now then it's probably better to pick up a Revelation/Yari or maybe a take off Fox Performance 36 or something.
I'm personally planning on running mine at 160mm front, else it will be too close to my other bikes. If you were thinking 160mm in your head, then perhaps 140 is indeed too short! As a note about offset bushings - there's a rumor that the santa cruz flipchip will be featured on this bike as well. If so, then no need for offset bushings unless you wanna go really low/slack.
I wonder if the upcoming cascade link would fit? If so, then we almost have a chinese megatower option!